Any intentional or unintentional loss caused by you to anyone, must be compensated by giving them back their full rights and seeking their real pardon, even if you give them more than the original amount because you have caused harm to them. If you don't know them, you should search for them through every possible way. After full search, if you could not reach to them or their families, you have to give their rights to the Marja of Taqleed so that he can spend it on their behalf.
Wassalaam